Analysis of α-amylase inhibitor from corni fructus by coupling magnetic cross-linked enzyme aggregates of α-amylase with HPLC–MS

Two-dimensional chromatography in screening of bioactive components from natural products

INTRODUCTION

Screening and analysis of bioactive components from natural products is a fundamental part of new drug development and innovation. Two-dimensional (2D) chromatography has been demonstrated to be an effective method for screening and preparation of specific bioactive components from complex natural products.

OBJECTIVE

To collect details of application of 2D chromatography in screening of natural product bioactive components and to outline the research progress of different separation mechanisms and strategies.

METHODOLOGY

Three screening strategies based on 2D chromatography are reviewed, including traditional separation-based screening, bioactivity-guided screening and affinity chromatography-based screening. Meanwhile, in order to cover these aspects, selections of different separation mechanisms and modes are also presented.

RESULTS

Compared with traditional one-dimensional (1D) chromatography, 2D chromatography has unique advantages in terms of peak capacity and resolution, and it is more effective for screening and identifying bioactive components of complex natural products.

CONCLUSION

Screening of natural bioactive components using 2D chromatography helps separation and analysis of complex samples with greater targeting and relevance, which is very important for development of innovative drug leads.

The Facile Preparation of PBA-GO-CuO-Modified Electrochemical Biosensor Used for the Measurement of α-Amylase Inhibitors' Activity

Element doping and nanoparticle decoration of graphene is an effective strategy to fabricate biosensor electrodes for specific biomedical signal detections. In this study, a novel nonenzymatic glucose sensor electrode was developed with copper oxide (CuO) and boron-doped graphene oxide (B-GO), which was firstly used to reveal rhubarb extraction’s inhibitive activity toward α-amylase. The 1-pyreneboronic acid (PBA)-GO-CuO nanocomposite was prepared by a hydrothermal method, and its successful boron doping was confirmed by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS), in which the boron doping rate is unprecedentedly up to 9.6%. The CuO load reaches ~12.5 wt.%. Further electrochemical results showed that in the enlarged cyclic voltammograms diagram, the electron-deficient boron doping sites made it easier for the electron transfer in graphene, promoting the valence transition from CuO to the electrode surface. Moreover, the sensor platform was ultrasensitive to glucose with a detection limit of 0.7 μM and high sensitivity of 906 μA mM⁻¹ cm⁻², ensuring the sensitive monitoring of enzyme activity. The inhibition rate of acarbose, a model inhibitor, is proportional to the logarithm of concentration in the range of 10⁻⁹–10⁻³ M with the correlation coefficient of R² = 0.996, and an ultralow limit of detection of ~1 × 10⁻⁹ M by the developed method using the PBA-GO-CuO electrode. The inhibiting ability of Rhein-8-b-D-glucopyranoside, which is isolated from natural medicines, was also evaluated. The constructed sensor platform was proven to be sensitive and selective as well as cost-effective, facile, and reliable, making it promising as a candidate for α-amylase inhibitor screening.

Magnetic particles for enzyme immobilization: A versatile support for ligand screening

Enzyme inhibitors represent a substantial fraction of all small molecules currently in clinical use. Therefore, the early stage of drug-discovery process and development efforts are focused on the identification of new enzyme inhibitors through screening assays. The use of immobilized enzymes on solid supports to probe ligand-enzyme interactions have been employed with success not only to identify and characterize but also to isolate new ligands from complex mixtures. Between the available solid supports, magnetic particles have emerged as a promising support for enzyme immobilization due to the high superficial area, easy separation from the reaction medium and versatility. Particularly, the ligand fishing assay has been employed as a very useful tool to rapidly isolate bioactive compounds from complex mixtures, and hence the use of magnetic particles for enzyme immobilization has been widespread. Thus, this review provides a critical overview of the screening assays using immobilized enzymes on magnetic particles between 2006 and 2021.

Recent applications of immobilized biomaterials in herbal analysis

Immobilization of biomaterials developed rapidly due to the great promise in improving their stability, activity and even selectivity. In this review, the immobilization strategies of biomaterials, including physical adsorption, encapsulation, covalent attachment, cross-linking and affinity linkage, were briefly introduced. Then, the major emphasis was focused on the reported various types of immobilized biomaterials, including proteins, enzymes, cell membrane and artificial membrane, living cells, carbohydrates and bacteria, used in the herbal analysis for bioactive compound screening, drug-target interaction evaluation and chiral separation. In addition, a series of carrier materials applied in biomaterials immobilization, such as magnetic nanoparticles, metal-organic frameworks, silica capillary column, cellulose filter paper, cell membrane chromatography, immobilized artificial membrane chromatography and hollow fiber, were also discussed. Perspectives on further applications of immobilized biomaterials in herbal analysis were finally presented.

Ethnopharmacology, phytochemistry, and pharmacology of Cornus officinalis Sieb. et Zucc

ETHNOPHARMACOLOGICAL RELEVANCE

Cornus officinalis (Cornaceae), known in Chinese as "Shanzhuyu," is a frequently used traditional Chinese medicine. It tastes sour and is astringent and slightly warm in nature. Its fruits have long been used to treat kidney deficiency, high blood pressure, waist and knee pain, dizziness, tinnitus, impotence, spermatorrhea, menorrhagia, and other diseases in China. The main distribution areas are Shanxi and Gansu.

AIM OF THE STUDY

This review focused on the ethnopharmacological uses of the herb. We also focus on the phytochemical, pharmacological, and toxicological studies on C. officinalis. The recent analytical methods developed for the quality control of the herb's constituents are also reviewed. Additionally, future trends and prospects in the study of this herb are proposed.

MATERIALS AND METHODS

Information on C. officinalis was gathered by searching the internet (PubMed, ScienceDirect, Wiley, ACS, CNKI, Scifinder, Web of Science, Google Scholar, and Baidu Scholar) and libraries.

RESULTS

This review compiled the ethnopharmacological uses, including the classic prescriptions and historical applications. Approximately 300 chemical compounds have been isolated and identified from C. officinalis. The major active components of the plant are organic acids and iridoids, among which morroniside and loganin have been extensively investigated. The fruit of the plant has been used in treating many diseases in traditional medicine. Scientific studies indicated the herb's wide range of pharmacological activities, such as hepatic and renal protection, antidiabetes activity, cardioprotection, antioxidation, neuroprotection, antitumor activity, anti-inflammation, analgesic effects, antiaging activity, antiamnesia, antiosteoporosis, and immunoregulation. The analytical methods developed for the quantitative and qualitative determination of various compounds in the herb were further reviewed.

CONCLUSIONS

In this paper, we reviewed various studies conducted on C. officinalis, especially in areas of its ethnopharmacological use, as well as on its phytochemistry, pharmacology, and modern analytical methods used. Some of the herb's ethnomedical indications have been confirmed by the herb's pharmacological effects, such as its hepatic and renal protection and the antidiabetic effects. In particular, the crude extract and its chemical composition have exerted good therapeutic effect in diabetic treatment. C. officinalis entails additional attention on its pharmacological effects and drug development to expand its effective use clinically. Many advanced technologies are used for quality testing, but the detection component is exceedingly scarce for synthetically evaluating the quality of C. officinalis herbs. Thus, further research is necessary to investigate the quality control and toxicology of the plant, to further elucidate its clinical use, and to control herbal quality.

Molecular Structure-Affinity Relationship of Flavonoids in Lotus Leaf (Nelumbo nucifera Gaertn.) on Binding to Human Serum Albumin and Bovine Serum Albumin by Spectroscopic Method

Lotus leaf has gained growing popularity as an ingredient in herbal formulations due to its various activities. As main functional components of lotus leaf, the difference in structure of flavonoids affected their binding properties and activities. In this paper, the existence of 11 flavonoids in lotus leaf extract was confirmed by High Performance Liquid Chromatography (HPLC) analysis and 11 flavonoids showed various contents in lotus leaf. The interactions between lotus leaf extract and two kinds of serum albumins (human serum albumin (HSA) and bovine serum albumin (BSA)) were investigated by spectroscopic methods. Based on the fluorescence quenching, the interactions between these flavonoids and serum albumins were further checked in detail. The relationship between the molecular properties of flavonoids and their affinities for serum albumins were analyzed and compared. The hydroxylation on 3 and 3’ position increased the affinities for serum albumins. Moreover, both of the methylation on 3’ position of quercetin and the C₂=C₃ double bond of apigenin and quercetin decreased the affinities for HSA and BSA. The glycosylation lowered the affinities for HSA and BSA depending on the type of sugar moiety. It revealed that the hydrogen bond force played an important role in binding flavonoids to HSA and BSA.

A simple and sensitive detection of glutamic-pyruvic transaminase activity based on fluorescence quenching of bovine serum albumin

It is well known that Cu(ii) can coordinate withl-alanine (Cu–Ala), which can be destroyed through the addition of glutamic-pyruvic transaminase (GPT) since GPT can effectively catalyze the conversion ofl-alanine into keto-acetic acid.